Sea Control is the one of
the primary roles of the RAAF, and the core capability of the RAN. The
ADF's current force structure in this area is based upon the 34 F-111s,
71 F/A-18s and 19 AP-3Cs using the Harpoon, AGM-142 and guided bombs,
operating in concert with surface vessels and Collins class SSKs using
the Harpoon and torpedoes to engage and destroy hostile maritime
surface
assets.

With force structure changes more than likely in the near
future, in response to a changing regional environment, and the nearing
decisions on the replacement of core assets such as the F/A-18 and
F-111, it is well worth exploring the basic issues in sea control and
looking at future options in strategy and technology.

The ADF's extant basic strategy for sea control was
independently developed, but in its fundamentals is basically the same
model which was developed originally by the Kriegsmarine and Luftwaffe,
and later shamelessly appropriated by the Soviet Voenno-Morskii Flot
and
Aviatsiya Voenno-Morskovo Flota. This model envisages the coordinated
use of land based air power and submarines to engage and destroy
hostile
surface vessels and any supporting assets, frequently at extended
ranges. In its fundamentals this is a very sound strategic model, and
was proven to be highly effective during the Battle of the Atlantic. A
disproportionate response in effort was required by the Allies to win
this battle against the Germans. The Soviet variant of this model,
based upon the use of the Tu-95/142 Bear, Tu-16 Badger and Tu-22M
Backfire (recently acquired by India), in conjunction with a wide range
of nuclear powered attack submarines, presented a formidable challenge
for NATO and would have tied down much of the USN carrier fleet in
times of war. Fortuitously this battle never occurred outside wargaming
tables and simulations. If the Soviet model had any weaknesses, these
were the same weaknesses the German model had - a failure to properly
coordinate operations between air assets and submarines.

The current ADF force structure model for sea control
operations is also not without it warts. While we possess over a
hundred
Harpoon capable aircraft, the F/A-18As are limited, without tankers and
well loaded with Harpoons, to a combat radius of about 250-300 NMI,
thereby leaving the outer operational radius to the F-111, AP-3C and
Collins SSKs. Only the F/RF-111C AUP is currently Harpoon capable due
to
delays in the F-111G upgrades, and the Collins SSKs are still in the
process of being made genuinely battleworthy. Moreover, the Collins is
limited in dash speed and dash endurance due to the primarily political
choice of classical diesel electric, over nuclear propulsion. The
absence of a genuine AAR fleet limits the reach of the F-111C/G to
about
800-1,000 NMI, and the F/A-18A with B-707-338C to about 800 NMI in
useful numbers, leaving only the AP-3C and Collins with the capability
to cover the extremities of the outer envelope.

The very improbable scenario of a an invasion fleet 300 NMI
off the coast could be dealt with decisively by the ADF - it is
arguable
how well even the USN could cope with a massive deluge of ASMs with
concurrent harassment by submarines. A single carrier CVBG could find
itself in much difficulty.

The bigger issue for the ADF in the coming decades will be
the
far more probable scenarios of India and the PRC interfering with sea
lanes to our north, and also potentially interfering with UN operations
in South East Asia. With no certainty on the issue of runway access on
the territory of our northern neighbours, we could find ourselves in
the
situation where the only assets with the required combat radius are the
AP-3C and the Collins SSKs. In terms of firepower both would be capable
of effective harassment attacks, however the AP-3C is not survivable in
the presence of fighters, and the Collins has a transit speed which
requires many days to position, and many days to get into safe airspace
for reloading with torps from a tender. Clearly this in not a credible
deterrent to hostile maritime operations by serious players in the
wider
region.

In established ADF-speak, the term "deterrence" is almost
exclusively reserved for precision land strike by the F-111 against
strategic fixed targets. The lame proposal to use the Collins as a
cruise missile shooter in this role was also centred on this model.

If current trends in Asia persist, it is likely that the
primary problem in deterrence will not revolve around turning fixed
ground targets into rubble, but rather keeping hostile naval and air
assets from operating in the region, and precluding the insertion of
military supplies via sealift and airlift. Therefore the deterrence
model we use needs to be broadened in its scope to encompass deterrence
against naval power and long range air power, as well as the
traditional
strategic target set. For this expanded deterrence to be credible, the
ADF will need to further evolve its force structure and its doctrine.

The most important capability required for such a model is a
decently sized fleet of strategic tanker aircraft, as this allows the
RAAF to extend the reach of the TFG and SRG to credible distances in
credible numbers (see AA Dec 99 - April 00).

Having the tanker fleet to deliver the firepower we need to
the distances we need is however only part of the solution. It will be
necessary to acquire targeting information in contested airspace, and
also perform Bomb Damage Assessment (BDA). Ideally a combat SAR
capability would also exist, since very long range operations always
run
the risk of fighters in the drink.

The currently envisaged role for the Collins SSK seems to
vary, depending upon whom you approach, but generally it is seen as
being best used to attack high value assets with torpedoes and provide
a
surveillance capability against hostile naval forces. With a sensitive
passive sonar, it has the ability to identify and track surface
contacts
without being detected from below the radar horizon of the contacts.

The traditional view is that the submarine goes in for a
torpedo attack while the RAAF rains Harpoons, AGM-142s and GBU-10s on
the opposing naval force. ASW ops using helicopters are not viable with
a sky full of hungry fighter pilots, and the combination of subsurface
and air attack is any convoy or SAG commander's worst nightmare.

Can this model be improved upon ? The limitation of the
Collins is its modest torpedo load, and once the acoustics are fixed,
its transit speed and endurance, especially when running quiet. If it
exposes itself, like any SSK, the opponent will most likely try to hunt
it down with ASW helicopters and surface vessels. While we can debate
the effectiveness of potential opposing ASW capabilities against the
stealthiness of the Collins, the reality is that once it starts
launching torpedoes its presence in the near vicinity is known. If we
budget two torps per target for a guaranteed kill, and assume the odd
torp goes astray in combat, we are up against the problem of how many
targets the SSK can concurrently engage and destroy in a surprise
attack, and how many times it can repeat such an attack.

This raises the question of whether the Collins is best used
as a "shooter", or whether this portion of the engagement is best left
to air power.

An alternative model is to use the Collins as a targeting and
BDA platform which supports air attacks by strategic tanker supported
F-111 and F/A-18, retaining its torpedo armament for defence against
ASW
forces if it is cornered or otherwise exposed, or for high value
targets
of opportunity. While such a use of the submarine may not be gratifying
to many of our naval enthusiasts, it is a model in which the Collins
exploits its strengths, which are stealth and towed passive sonar, and
avoids its weaknesses of limited firepower and submerged endurance /
dash speed. The other side of this model is that the strengths of air
power, rapid transit, massive firepower and flexibility, are best
exploited, without incurring the large overheads of tanker supported
and fighter escorted targeting recce and BDA sorties.

While it may be argued that an AP-3C or even an RQ-4A Global
Hawk can perform the targeting recce and BDA roles better, an opponent
using good emission control practices, running electromagnetically
silent, must be hunted down using radar. Any radar transmission by the
AP-3C or Global Hawk betrays its position, identity and possibly
intent.
Only passive sonar can provide genuinely undetectable maritime target
detection, tracking and identification which denies the opponent any
warning.

In practice, this doctrinal model would see the submarine
detecting and shadowing a hostile SAG, CVBG or convoy, carefully
developing a situational picture using its passive sonar system to
identify and count the types of targets and their positions in the
area.
Budgeting 4-8 hours for a strike force to arrive, the submarine raises
a
communications mast and uses a covert LPI (Low Probability of
Intercept) satellite link to transmit the situational picture to a
maritime operations HQ. From there the strike mission is tasked and a
tanker supported fighter package is sortied to engage the target set.
The submarine then uses its covert satcom link to get the estimated
arrival time of the strike force. Once the fighters arrive, the
submarine could datalink the current tactical picture to the fighter
package, thereby allowing them to approach without using radar to alert
the targets. Once the package knows the exact position and types of
target, the fighters can light up their radars, pick targets and start
shooting missiles.

Once the missiles hit their targets and the package departs
for home, the submarine can move in closer to assess the number of
kills, and if conditions permit, finish off damaged vessels using
torpedoes. This is an economical use of the submarine's warload, and
its
use under conditions where the opponent is unlikely to be in the
position to mount an effective ASW response. Once this phase of the
strike is completed, the submarine can move to a safe distance and use
its covert satcom link to send the BDA results to maritime HQ. If
another air attack is warranted, then the profile is repeated.

This "combined force" use of the SSK and air power also has
the advantage of allowing the submarine to remain in the patrol area
longer, rather than departing after one or two engagements, due to
having expended its warload. Fuel and supplies permitting, the less
torpedoes are expended, the longer the sub can remain active in the
area
and therefore the greater its effectiveness given the slow transit
speed
to an operating area.

Surprise is always a decisive advantage in combat, and this
model is designed precisely for that, since the opponent's first
warning
is the activation of targeting radars and the launch of Harpoons.
Depending upon the launch geometries the warning time before missile
impact could be as short as several minutes. If a weapon like the
AGM-142 is used and launched against the primary AAW asset off
targeting
coordinates provided by the submarine, this asset may have a warning
time of seconds.

Much depends upon the quality and currency of targeting
coordinates which the submarine can datalink to the strike aircraft. If
the information is of sufficient accuracy and recency, then the
Harpoons
could be targeted silently and launched from below the radar horizon of
the target shipping. Therefore the first warning is when the Harpoon
seekers light up, seconds from impact. Unless the primary AAW radar of
the defending vessel is good enough for early detection of the
Harpoons,
the first warning will be the ESM alarm identifying the Harpoon
seekers.

Adapting the Collins SSK

The minimal adaptation to the Collins SSK to support this
regime of operations is the installation of a covert LPI digital
datalink capable of relaying targeting coordinates, and other messages,
over a satellite link.

The big difference between a covert link, and a conventional
link, is that the covert link must not betray the submarine to hostile
ESM or active radar searches of the patrol area. The best strategy for
defeating ESM is to use a centimetric band highly directional pencil
beam, a very low sidelobe antenna, and a spread spectrum waveform for
the datalink signal. To defeat radar searches, the antenna mast and
antenna must have a very low radar cross section. In essence the same
caveats which apply to the design of an LPI radar on a stealth aircraft
apply to the antenna installation on the sub. However, since the
antenna
mast will be grazing the surface, and weight is a much lesser issue,
the
demands are much lesser than for a combat aircraft.

The most practical choice is the adaptation of an existing
active phased array antenna designed for a fighter aircraft, installed
in a faceted fairing on top of a mast. The antenna boresight would
point
vertically upward. An issue will be the choice of antenna design, or
its
adaptation, to match a centimetric band satellite repeater. This type
of installation, if done properly, can have a negligible radar cross
section, especially for the shallow grazing angles typical of search
radars. Since the operating areas are mainly equatorial, geostationary
satellites will be directly overhead or at very modest deflection
angles. A typical fighter radar has a beamwidth of about 3 degrees,
which is well suited for this application.

The motion of the submarine is easily compensated if a phased
array is used, and the appropriate pointing angle is easily calculated
in software, since the submarine has an accurate navigation system and
the position of the satellite is fixed. The absence of moving parts
means the design can be very reliable. It is worth noting that other
choices also exist for doing this, such as a tethered floating antenna
with optical fibre cable embedded in the tether.

Direct relay of coordinates between the submarine and
aircraft
is cumbersome, and a very simple alternative is to exploit yet again
the
satellite, to relay the signal to a tanker aircraft equipped with a
suitable satellite transceiver and JTIDS datalink master station. It is
expected that JTIDS will be a standard fit on all RAAF combat aircraft
by the end of the decade, so no additional expenses are incurred in
this
respect.

What could present a problem is submerged endurance and speed
vs noise, especially when shadowing target shipping. SSKs excel in the
stealthy ambush, but do not perform well in sustained dashes due to the
need to snorkel and recharge batteries. Therefore appropriate tactics
would need to be developed, especially when dealing with fast SAGs or
CVBGs.

In the longer term, air independent propulsion must be a
serious consideration. There have been promising developments in a
number of areas, such as hydrogen-oxygen fuel cell technology, which
could be applied eventually. While near term choices are centred on
schemes such as air independent diesels or Stirling engines, both are
potential noise sources due to moving parts.

Fuel cells are fed on a flow of hydrogen and oxygen, and
produce electricity and water when these are combined, with no moving
parts. Of course, it is not practical to fuel an SSK (or a car) using
tanks of LOX and LH2 ! Current trials in the automotive area involve
the
use of compressed air, and hydrogen produced by breaking down a liquid
fuel such as gasoline, methanol or diesel in a chemical reactor, termed
a "reformer", which performs catalytic cracking. Therefore the
propulsion package is fed on a liquid fuel and air, produces
electricity
with no moving parts other than compressors for the air, and is
virtually silent.

For a non-nuclear submarine, the attraction of this approach
is that the size of the batteries can be significantly reduced and the
freed volume used for the storage of compressed air or oxygen and
possibly, more fuel. Since compressed air or oxygen are used,
compressors for the air feed to the cell may not even be required.
Current PEM (Proton Exchange Membrane) technology fuel cells being
trialled for automotive use have demonstrated power densities of around
1 kiloWatt per litre of cell volume, and are regarded to be scalable up
to 10 MegaWatt power levels, which is in the required class to drive an
SSK (see IEEE Spectrum Nov 98). For comparison the Collins is driven by
a Jeaumont Schneider 5.4 MW DC motor. In an SSK application, the PEM
cell directly drives the main shaft motor, and charges if required the
backup batteries.

Instead of snorkelling to expel diesel exhaust and draw air,
the sub would snorkel only to replenish its compressed air supply.

An interesting benefit of using a hydrogen / oxygen fuel cell
is that hydrogen can be tapped off to drive a Sabatier reactor carbon
dioxide scrubber (technology being developed by NASA for Mars
missions).
This would allow the sub to rid itself of carbon dioxide without
consuming oxygen candles or electricity, as long as it has supplies of
compressed air and fuel it can remain submerged.

How soon PEM technology will be mature enough for an
operational SSK application remains to be seen. HDW are currently
testing a large Siemens PEM fuel cell for the Bundesmarine,
specifically
for use in the 212 class SSK. This PEM module is claimed to have a
conversion efficiency of about 70%. The big issue will remain the
design of the reformer modules for efficiently converting hydrocarbon
fuels to hydrogen and waste products. If current trends continue the
technology may be available for use by 2010, around the time the
Collins
boats become due for midlife refits.

Air Power Issues

To support such a regime of submarine based targeting and
BDA,
the principal requirements are sufficient numbers of big tankers and
the
appropriate satcom datalink and JTIDS capability on some of these,
which
would become defacto airborne command posts for the strike packages.

While the F-111 and the F/A-18 remain our primary combat
aircraft, existing weapons and delivery techniques would suffice. The
interesting question which arises is that of adapting the future AIR
6000 replacements to the maritime strike role.

Should the RAAF opt for evolved teen series generation
aircraft, such as the F-16/Block 60, the F/A-18E, the F-15E/K, the
Typhoon or the Rafale, then the existing weapons technology, ie the
Harpoon and AGM-142 for standoff attack, and the laser guided bomb for
close-in attack, would be retained or replaced with future equivalents
and the established tactics adapted as required. Established weapons,
established tactics and established cost structures.

What about the stealthy F-22 and the planned F-32/35 JSF,
should it reach production ? These types are built to exploit stealth
and clearly outclass teen series generation aircraft in the counter-air
and land strike roles. For strike missions they are intended to
penetrate high and fast, indeed the F-22 does so at 45 kft+ and Mach
1.4, delivering GPS guided GBU-31/32 JDAMs.

Stealth requires internally carried weapons, and modestly
sized bays designed around 1,000 lb JDAMs will not fit the Harpoon or
similar ASMs. Penetrating at stratospheric altitudes and supersonic
speeds is not a viable launch environment for Harpoon class ASMs. Even
should a supersonically rated ASM be built, it is unlikely to fit into
an internal bay, and carried on a pylon compromises stealth and incurs
costly drag.

The solution to this problem, for direct antishipping strike
and for naval mining, turns out to be simpler than one might expect -
derivatives of the GPS guided JDAM bomb.

For antishipping attack a radar terminal seeker for the JDAM,
derived from established millimetric wave or IR seekers designed for
anti-tank munitions, is neither a costly nor a complex adaptation. The
fighter would use its radar to track the intended target vessel, the
bomb would be programmed with the "no escape" footprint for the ship,
and released. Using its conventional JDAM GPS/inertial guidance, it
would fly itself to a point above the acquisition footprint, point
itself vertically down and activate the radar seeker. Once it has
located the ship, it would home in and vertically punch through the
superstructure or upper decks at supersonic speed.

It is worth commenting here that the major air-sea battles of
WW2 in the Pacific were won primarily by the humble SBD Dauntless dive
bomber, delivering 1,000 lb bombs in steep diving attacks. The targets
were typically very well armoured by today's standards.

The lethality of a radar seeker equipped antishipping JDAM
variant could be significantly enhanced by using the smart fuse
technology devised for bunker busting bombs. These fuses have an
internal accelerometer to allow them to pick which cavity to explode
in.
For an antishipping application, the bombs would be programmed to
explode once they have punched through beneath the keel of the ship, in
the same place modern torps are designed to explode. If a pair of JDAMs
is dropped and the fusing programmed for a fraction of a second of
delay
between the bombs, they could achieve a similar effect to a dual pulse
torpedo warhead, and break the back of the ship.

Attacking in a vertical dive, the bomb arrives in what is a
traditional blind spot for ESM and defensive radar coverage. Even if
the
ship's superstructure is faceted to beat an ASM seeker or search radar,
decks are always nicely flat so the radar cross section is enormous.
The
millimetric wave seekers developed for killing tanks could thus be
easily adapted for this purpose. An Infrared (IR) seeker may be
cheaper,
but is weather limited.

For mining operations, the JDAM can also be adapted. Several
existing USN air delivered naval mines simply use Mk.80 series bombs
with appropriate fusing kits. The issue for mining is to achieve an
accurate low speed delivery. For a JDAM derivative naval mine dropped
at
supersonic speed and 40 kft+, this is a first glance a problem issue.
However, the JDAM is designed to fly shaped trajectories, and
adaptation
of the autopilot software would allow the bomb to be programmed to fly
a pull-up before impact, to bleed off most of its energy, and arrive at
the intended aimpoint at a very low speed.

From a force structuring perspective, the nice aspect of
these
proposed weapons is their inherently low cost, yet high lethality. Even
if the anti-shipping seeker adds USD 50k, a reasonable estimate, to the
cost of a USD 15K JDAM kit, the weapon is still a fraction of the cost
of a Harpoon or a guided torpedo, yet delivers a 1,000 lb warhead at
supersonic speed. Such economics are difficult to argue against. The
economic advantage in turn means that larger stocks can be kept, still
at a total cost advantage, and this improves sustainability. Since such
derivative weapons are based upon extant technology, developing them
incurs little risk or cost, against a new generation ASM design.

Maritime JDAM variants delivered by stealthy fighters offer
the very same economic advantages offered by the stealth delivered
standard JDAM against standoff missiles or cruise missiles. Moreover,
tactical conditions permitting, such weapons could also be delivered by
conventional fighters. Since they are cheap, they are a viable choice
for killing low value targets such as Fast Patrol Boats, missile boats,
and barges.

Clearly the technology base now exists which would allow the
use of the F-22 and the JSF in the maritime strike roles currently
occupied by the Harpoon firing F-111 and F/A-18A. Given the timelines
for AIR 6000, these aircraft become viable candidates across the whole
role spectrum currently performed by the RAAF's SRG and TFG.

In summary, it is clear that viable alternative choices exist
in doctrine and technology to support the sea control and maritime
deterrence missions over coming decades. Our defence planners should
consider this carefully in the upcoming force structure and acquisition
debates.

The limitation of the
RAAF's
current force structure in maritime strike scenarios is poor operating
radius. While the R/RF-111C and F/A-18 are Harpoon capable, the latter
requires tanker support for anything beyond trivial radii, while the
former is limited to about 1,000 NMI. The AP-3C is not survivable in
the
presence of hostile fighters and modern SAMs. To produce a credible
maritime deterrent, a robust number of strategic tanker aircraft will
be
required. The Collin SSKs can provide an effective recce and BDA
capability to support the RAAF in such operations thereby significantly
reducing the operational overheads incurred in the targeting cycle
(RAAF
PR).

SSG-75 HMAS Waller. The Collins
SSK, once fully
operational, has much potential for use as a targeting reconnaissance
and Bomb Damage Assessment platform, supporting long range
anti-shipping
strikes by strategic tanker refuelled fighters. Its use in this role
requires that a covert LPI satellite communications link be added, to
relay targeting and BDA information to the aircraft. Using it for
targeting and BDA exploits its stealth, on station endurance and
capable
sonar and systems, while exploiting the short response time of air
power, and its massive and sustained firepower (DoD).

This
hapless destroyer was hit by a Mk.48 torpedo launched from a
Collins SSK. The torpedo exploded under the keel and broke the back of
the ship. A similar effect can be achieved by a GBU-31/32 JDAM if the
HTSF smart fuse is employed, and the bomb set to explode once it
punches
through the bottom of the target vessel. At a fraction of the cost of a
Harpoon or a torpedo, a seeker equipped JDAM would deliver
unprecedented bang for buck (DoD).